Difference between below material

[MQM90]

Can i know the difference from point of view of thermal expansion & the role of different compositions.

Basically we are checking our exsiting superheater for new superior materials.

In general i know for higher grades the thermal conductivity decreases and the elasticity gets better(due to addition of alloying elements).

Design Temperature of flue gas in shell: 1400 deg C
Steam water temperature in tubes is ~ 500 deg C

Following are materials

1. SA-213 T12 Vs SA-213 T22 - TUBES
2. SA-335 P12 Vs SA-335 P22 - HEADERS
3. SA-209 T1 Vs SA-234 WP 91 - BENDS

and we are checking superior grade i.e. SA-213 T22 , SA-335 P22 and SA-234 WP 91 against existing materials i.e. SA-213 T12 , SA-335 P12 and SA-209 T1 as the existing materials are causing sagging of tubes.

Appreciate your fast response, please

Its urgent.

Osama


Osama Nusrat Ali

 

[unclesyd]

The thermal expansion is for all practical purposes the same, it's creep resistance needed

Are you sure that the sagging isn't caused by creep?

What is the service life of the existing material?

is the sagging localized or is all tube affected?

There are several people in this forum that will be able to give a little more information about the creep resistant of your proposed materials.

 

[MQM90]

Point wise reply is as follows

Thankyou for answering me.

1. No i m not sure that sagging is caused by creep or not ?
2. 30 years - service life
3. the sagging is overall

Please continue

Osama Nusrat Ali